Combination key seat remover and vibration distributor for well drilling



Oct. 30, 1951 J. MOCLINTON COMBINATION KEY SEAT REMOVER AND VIBRATIONDISTRIBUTOR FOR WELL DRILLING 3 Sheets-Sheet 1 Filed Oct. 25, 1947 J 0HN MECLINTON JNVENTOR. wn a. M

ATTORNEY! J. M CLINTON Oct. 30, 1951 5 Sheets-Sheet 2 Filed Oct. 25,1947 7 5 z l a 7 V l w 3 7 l k 1 l 4 gigfig Oct. 30, 1951 J. MCCLINTON2,572,839

COMBINATION KEY SEAT REMOVER VIBRATION DISTRIBUTOR FOR WELL D LLINGFiled Oct. 25, 1947 3 Sheets-Sheet 3 JOHN MECLINTON INVENTOR. BY m A TTOIQ/VE VS Patented Oct. 30, 1951 COMBINATION KEY SEAT REMOVER ANDVIBRATION DISTRIBUTOR FOR WELL DRILLING John McClinton, Houston, Tex.

Application October 23, 1947, Serial No. 781,724

6 Claims.

This invention relates to an apparatus and to a method of removingformations around slots or bores of lesser than drill collar and drillbit diameter such as a bridged portion in the well bore through which itmay become necessary to elevate the drill collar and bit of a drillingassembly in Withdrawing them out of a well.

This invention also utilizes the same apparatus to minimize thevibratory stresses and strains which travel upwardly from a drilling bitthrough the drill collar to the tool joints and drill pipe of a drillstring.

It often occurs in the drilling of wells by the rotary method wheredrilling fluid is circulated into and out of the well bore that thedrill bit while rotating and IIlOVlIlg downwardly by penetrating intothe earth may strike an obstacle, usually in the nature of a hardsubterranean formation having layers or planes which slant from thevertical. Such an obstacle might be a boulder or crevice which deflectsthe bit away from the vertical. The bit thus will drill a defiectedcourse determined by the slanted plane or face of the hard formation.However, as the bit and flexible drill pipe rotate, the pull of gravityon the drill string tends to return it to a straightened course, and intime the bit returns to drilling a perpendicularly downward course whichmay or may not substantially coincide with the general vertical axiswhich was being drilled prior to the deflection of the bore.

The drilling trades define as a dog leg the formation between thiscurved or deflected bore section and a substantially vertical axisjoining the generally vertical bore above the deflection with thegenerally vertical bore which the bit resumes drilling below it.

As the dog leg is formed the drill pipe above the drill collar followsthe bit around the bend and rotates in the curved dog leg bore. In timethe natural tendency of the pipe to straighten and the weight thereofagainst the inside of the bore wearsaway the formation in the directionof the generally substantially vertical axis of the bore which the bitis drilling and finally wears a slot into the dog leg formation. Thepipe thus. rotates and moves vertically in such slot or bore which hasbeen cut substantially coincidental with this generally substantiallyvertical axis of the well bore. The diameter of this new bore is lessthan that of the bored hole because it has been determined by thediameter of the drill pipe tool joints which have cut the slot as thedrill pipe rotated and moved downwardly. Such slot is consequently ofsmaller diameter than the bore diameter which the bit has drilled. I

The bit may have drilled hundreds or even thousands of feet of boredhole below the do leg before the bit becomes dull or for some otherreason is to be withdrawn from the borehole.

Obviously the larger diameter drill collar and bit cannot be pulledupwardly through the restrictive bore and a certain amount of formationwill have to be removed from around the slot or bore which the tooljoints have worn as a result of the drill string seeking an alignedaxis. In withdrawing the drill string from the well, the drill collarWill wedge in the narrow slot between the substantially vertical boreabove and below the dog leg. The trade defines as a key seat thisformation which has to be removed to permit the upward passage orwithdrawal of the drill collar and bit. It follows then that the slot orbore, which the tool joints have cut as the drill string seeksalignment, is called the key seat bore.

An object of this invention is to provide an apparatus and a method forremoving or enlarging a key seat to permit the drill collar and drillbit of a drill string to be withdrawn upwardly therethrough when thedrill string is being pulled out of a well.

Another object of this invention is to provide an apparatus and a methodwhich will remove a key seat so that the drill collar of the drillstring may be drawn upwardly therethrough and pulled out of the well.

Still another object of this invention is to provide an apparatus and amethod in which an upwardly and inwardly tapered threaded broach ismanipulated to remove a key seat by cutting and shearing the formationthereof to enlarge.

the key seat to a diameter slightly larger than a drill collar.

A further object of this invention is to provide an apparatus and methodwhich minimizes the torque and lift required to be exerted at thesurface of the well, by virtue of the combined shearing and cutting ofrestrictive key seat formations by a tapered threaded broach included inthe drill string assembly.

Still another object of this invention is to provide an apparatus andmethod in which an inwardly and upwardly tapered broach has modifiedacme threads thereon provided with cornered edges, so that the threadscan more effectively shear and cut out a key seat formation.

Yet another object of this invention is to provide an apparatus and amethod of use thereof in which an inwardly and upwardly tapered threadedbroach which has become stuck in a restrictive formation, such as a keyseat, can unscrew itself downwardly as the drill string is rotated untilgravity pulls the whole drill strin downwardly from the key seatformation.

A still further object of this invention is to provide an apparatus inthenature of an upwardly and inwardly tapered broach inserted as aflexible element between drill collar and tool joint of the lowest drillpipe section, so as todampen and minimize the drilling vibrationstransmitted upwardly from a drill collar to tool joints and drill pipeof substantially smaller diameter than the drill collar.

Other objects and advantages of the device of this invention will bemade apparent through the following description taken in connection withthe drawings in which:

Fig. l is an elevation, part in section, which shows part of a drillstring which is bein pulled out of a well, just before the broach ispulled up into the key seat.

Fig. 2 is a horizontal section of the well bore just. above the dog leg,taken on line 22 of Fig.1.

Fig; 3. is a horizontal section through the dog leg. above the point ofgreatest deflection, and after the key seat has.been worn, taken on line3.3'of Fig. 1.

Fig. 4; is a. horizontal section through the dog leg near the point ofgreatest deflection, and after the key seat has been worn, taken on line4 -4 of- Fig. 1'.

Fig. 5 isa horizontal section taken through the well bore and: thethreaded: broach at its lowest part, taken on line 5-5 of Fig. 1.

Fig. 6 is a sectional elevation which for purposes of illustration showsa dog leg of exaggerated curvature and a key seat bore of shortenedlength in the processof being enlarged, and which shows the broach ashaving just beenpulled upwardlyuntil it is about to bind in the keyseatz"formation-.

' Fig. 7- isa horizontal section taken through the well bore above thedog leg, taken along line T-II of Fig. 6.

Fig. 8 is a horizontal section through the dog leg'above'thepoint ofgreatest deflection, taken along line 88=of Fig. 6.

Fig. 9 is a horizontal section through the dog leg near the point ofgreatest deflection, taken along line 9-9 of Fig. 6.

Fig. 10 isa horizontal section through the drill collar below the dogleg.

Fig. 11 is an enlarged partial elevation showing the details of thebroach thread construction.

Referring indetail to'the drawings, the pathof drilling is. shown ashaving passed through an ordinary earthen formation I and into anexceptionally hard or rocky formation or a deflecting subterranean body2. Sucha formation has deflected the drill bit, not shown, along thedeflecting face tat an angle-tothevertical bore 5. The path from whichthe general vertical bore 5 of the well is thus deflected is shown asthe dog leg 4. The general vertical bore 6 is gradually resumed belowthe dog leg 4 after the bit passes by the base of the obstacle ordeflecting formation 3.

As the drilling of the bore continues the rotating pipe bearing againstthe inclined surface 3 on the inside of the bore 4 wears away theformationso that a slot Q'iscreated by thepipe and the tool joints. Thepipe eventually tends to straighten itself andwearsaway the key seatwhich is de- 4 fined by the bore "I in the formation at 8, and the slot9 which has been worn in the formation l and I0 between the deflecteddog leg bore 4 and the bore I.

A section of the drill string II is shown in Fig. 6 as a combination ofthe drill pipe I2, the tool joint I3, which connects the drill pipe [2and the broach I4, and the drill collar I5. The bit, not shown, isattached to the end of the drill collar I5. The broach I4, which is botha key seat remover and vibration distributor as will be hereinafterdescribecl,.has been inserted in the drill string directly above thedrill collar I5. A drill bit, not shown, is attached to the lowest partof the drill collar.

The externally threaded lower pin end I6 of the drill pipe l2 has asshown in Fig. 6. the internally threaded upper end I8 of the tool jointI3 threaded thereon. The externally threaded lower end ll of the tooljoint I3 is threaded into an internally threaded upper portion I9 of thestraight-sectioned, unthreaded upper end 20 of the broach I4. Thisupperbroach end 20- is of substantially the same outer diameter as the body21 of the tool joint I3. The broach I4 has a reduced, externally taperedthreaded lower end 22 which is screwed into the internally threadedupper end of the drill collar I 5 The drill collar isofl'argerdiameterthan the drill pipe to provide weight and rigidity to prevent unduedeflectionof the bit.

The broach I4 has a tapered threaded section 23 on which the threadsdecrease in diameter upwardly, the lowest full thread 24" being of adiameter slightly in excess of the outer diameter of the drill collarI5, while the uppermost full thread 2-5 is only slightly greater thanthe outerdiameter of theupper'broach end 20 and thetool joint I3. Thebroach thread contours are shown as having upper and lower edges 26 and27 respectively, which are substantially a standard acme profile madedished or concave along the vertical width 28 thereofso as to increasethe cutting or shearing action in cutting awaythe bore 1.

In ordinary drill strings, in point of space and time, breakage islikely tooccur where" the drill collar, of larger diameter, is" joinedto the drill pipe of smaller diameter and this breakage is likelytooccurwhen the bit has resumed drilling a substantially vertical courseafter having finished drilling the course of a dog legsimilar to.that-shown in Fig. 1. This result is obviously due to the fact that the:vibratory effects transmitted upwardly from the bit are enhanced inpassing upthrough the portion of the. drill collar I5 which is in asubstantially vertical" bore, and on upwardly'into the drill pipeI2,,which. is whipping about in the dog leg 4. And it is pointed outthat this breakage occurs at the point of junction of drill pipe-anddrill collars because of the abrupt change in diameters-between thelarger drill collar and the comparatively smaller drill pipe.

The insertion of thebroach I4 of this invention between drill collar I5and drill pipe I2 designs toobviate these causes of breakage byproviding an element which is tapered over its length 23 from the bottomthread 24' upwardly to. the broach end 29. Thisamounts to a considerablethreaded length 23 which provides flexibility as. a

bridging connection between drill collar and drill".

pipe. At its point of connection 22 to the drill collar I5 the broach I4isof' essentially drill coll'ar diameter, but, as shown in Fig; 6, evenat this point the broach must be of lighter weight and To move the drillstring II up through a key seat formation 8, and to enlarge the key seatbore! so as to remove the key seat, strain is put on the drilling stringat the surface-of the well and the string is pulled upwardly. If drag isregistered at'the surface, it is indicative that the broach M has movedinto binding contact with the key seat formation 8.

If the formation is not too hard it may be possible, by exerting bothstrain and rotational torque at the surface, to move the broach l4completely up through the key seat without it ever becoming bound orstuck in the restrictive formation. The upward strain pulls the upperthread corners 26 into the key seat formation 8, and the lead of thethreads, when the broach is rotated, tends to shear or cut the formationto enlarge the key seat 1. The threads tend to carry the formationcuttings downwardly into the well bore around the drill collar l5 belowthe key seat.

When the upward pull on the drill pipe is exerted at the surface of thewell, with or without accompanying rotation, the broach I4 is moved upinto the key seat formation 8 until it wedges therein. The pull may thenbe slackened off the drill string. If weight alone does not loosen thebroach from such wedged position, thegdrilling string may be rotated inaddition. This rotation will cause the broach threads to shear or cutaway the formation 8 and move it downwardly. The rotation, aided by theweight of thepipe, drill collar, and bit, will cause the broach tounscrew downwardly so that there is vertically downward motion of thewhole drill string. Finally the weight of the drill string below thelocality of the binding formation overcomes the binding friction of theformation against the section of broach threads still in contacttherewith, and the broach then shears away this binding formation asgravity acts on the drill string weight. This process of pulling up,rotating, slackening on weight, and rotating, may have to be repeatedseveral times before a hard key seat is enlarged by removing theformation to permit the upward passage of the drill collar and bitthrough a sufficiently enlarged key seat bore.

The use of drilling mud in the rotary method of drilling wells is a wellknown and essential part of such operation, the mud being circulateddown the drill pipe from the top of the well and up the well boreoutside of the drill pipe. As the top thread 25 of the threaded sectionof the broach is larger in diameter than the broach end 20, and as thebottom thread 24 is larger in diameter than the drill collar I5, mudcontinuously fills the key seat bore 1 in the space between the broachthreads and around the body thereof, and this mud acts as a lubricantbetween the broach and the key seat formation 8, both when the broach ispulled upwardly, moved downwardly, or rotated. This mud, by gravity,also flows around the drill collar when it is 6 pulled up into the keyseat. Thus, this continuous presence of mud insures a lubricant,opposing any condition tending to cause sticking of the broach or drillcollar.

The lubricating function played by the mud combines with themanipulation of the broach after the manner in which a rat tail file ismanipulated in enlarging a hole in wood. By repeating, in the presenceof a lubricant, the steps of pulling the broach upwardly into the keyseat until it sticks, rotating it to loosen it, and then moving it upand down to shear away the formation between the threads cut by therotation of thebroach, it is possible to remove the formation around thekey seat bore to permit the upward passage of the drill collartherethrough. Then the bit on the end of the drill collar, which is oflarger diameter than the drill collar, may be worked upwardly throughthe enlarged bore by rotating the drilling string.

It is also obvious from the construction of the broach that it has afunction in wearing away dog leg formations, or any restrictiveformations in the bore, as the bit drills downwardly. This results byvirtue of the threaded construction ofthe broach which brings itsthreads into cutting contact with the dog leg wall in the direction ofcurvature.

The application of lifting strain, the slackening of the pull, and therotating of the drill string, are determined by the key seat formation,and many combinations and sub-combinations of these forces, aided by thelubricating effect of the mud, may be utilized in employing theapparatus and method of this invention.

Broadly the invention contemplates the insertion of a tapered, threadedelement with wider portion downward, into a drill string assembly sothat restrictive formations can be cut away by the threads and so thatthe weight of the drilling string below the element will act to pull theelement downward and shear out the formation. Broadly the invention alsocontemplates the employment of such a tapered element to distribute anddampenvibrations transmitted upwardly through the drill string from thedrill bit and drill collar when the bit is drilling.

What is claimed is:

1. A hollow broach comprising a tapered, externally threaded body to beconnected into a drill string used in rotating the drill bit in therotary method of drilling wells where such string includes sections ofdrill pipe connected with tool joints and drill collars connected to thebit, means on the upper end of said body to connect to a tool joint,means on the lower end to connect to a drill collar, the uppermostthread dimension being of the smallest diameter but slightly greaterthan the diameter of said tool joint thereabove, the lowermost threaddimension being of the largest diameter and slightly greater than thediameter of said drill collar therebelow.

2. A hollow broach comprising a tapered, externally threaded body to beconnected into a drill string used in rotating the drill bit in therotary method of drilling wells where such string includes sections ofdrill pipe connected with tool joints and drill collars connected to thebit, means on the upper end of said body to connect to a tool joint,means on the lower end to connect to a drill collar, the uppermostthread dimension being of the smallest diameter but slightly greaterthan the diameter of said tool 7 joint, thereabove, the "lowermostthread dimension being of the largest diameter and slightly greaterthan-the diameter of said drill collar therebelow, said threads being ofsubstantially acme profile.

3r. A hollow broach comprising a tapered, externally threaded body to beconnected into: a drill string used inzrotating the drill bit in therotary method of drilling wells where iSlICh string,

includes sections of. 'drillpipe connected with tool gjoints.and-drill'collars connected to the bit, means .on the upper end .ofsaid .body to connect to a tool joint, means on the lower end to connectto .a-drill collar, the uppermost thread dimension being of the smallest:diameter but greater thanthe. diameter of said tool joint, thereabove,the lowermost thread dimension being of. the largest diameter andslightly greater. than the diameter of saiddrill collar therebelow, saidthreads being of substantially acme profile with the vertical widthsthereof dished. 1 4. A hollow bro'ach comprising a tapered, externallythreaded body to be connected into a drill string used in rotating thedrill bit in the rotary method of drilling wells wheresuch stringincludes sections of drill pipe connected with tool joints and drillcollars connected tothe bit, means on the upper end of said body toiconnect to :a tool joint, means. on the lower end to connect to a drillcollar, the uppermost thread dimension being of the smallest diameterbut slightly greater than th'ediameter'of said first means and said tooljointthereabove, the lowermost thread dimension .being :of the largestdiameter and slightly greater than the diameter of said secondmeansandsaid drill collar therebelow.

5. Ahollow ibroach comprising a tapered, externally threaded body tobe'connected into a drill string used in rotating theclrillbit in therotary method of drilling wells where such string includes sections ofdrill pipe connected with tool joints and drill collars connected to thebit, means Jon the upper end of said body toconnect to .a tooljointglm'ean's nn'pth'e lower end to connect to a drill collar, theuppermost thread dimension v being of tlie'rsm'allest diameter butslightly greater than the diameter of said tool joint thereabove, thelowermost thread dimension being of :the :largest :diameter and slightlygreater than the diameter of said drill collar therebelow, said taperedthreadsbeing cut to a sizeable profile to removec'sufiicient stock fromsaid body to render. said breach substantially flexible.

6; A key seat remover tool to be rotated by a drill pipewin rotarydrilling comprising a taperedrtu-bular body, a-ipipe connection 'at eachend of said body to position said body. in the drillpipe withthesma'ller "end of the taper up, a coarse shearing threadon theperiphery of said body so thatasthetoolis rotated, raised, and lowered,in a restricted area in a well bore such area will ,beenlarged by themovement of such coarse thread and the surging of Well liquid in thearea'to :lubricate 'the tool.

JOHN MCCLINTQN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 52,632 Whittlesey Feb. .13, 1866615,427 C'asaday Dec. 6, 1898 1,269,970 Smith June 18, 1918 1,371,425Jones M Mar. 15, 1921 1,602,794 Erwin Oct. 12, 1926 1,725,298 PickinAug. 20, 1929 1,8d8,l28 Hinderl-i-ter Mar, 8, 1932 2,028,910MacClatchie: Jan. 28, 1936 2,107,547 Pyle Feb. 8, 1938 2,210,824 WalkerAug. 6, 1940 FOREIGN PATENTS Number Country Date 317,125 Germany Mar.15, 1916 525.176 Germany May 20, 1931

